Abstract

Spin precession and dephasing (“Hanle effect”) provide an unambiguous means to establish the presence of spin transport in semiconductors. Theoretical modeling was compared with experimental data from drift-dominated silicon spin-transport devices, illustrating the non-trivial consequences of employing oblique magnetic fields (due to misalignment, or intentionally fixed in-plane field components) to measure the effects of spin precession. Model results were also calculated for Hanle measurements under conditions of diffusion-dominated transport, revealing an expected central Hanle peak widening effect induced by the presence of fixed in-plane magnetic bias fields. The use of two-axis magnetic fields to reveal incoherent spin precession in quasi-lateral spin transport devices was discussed.

Spin-valve transistors with palladium (Pd) base layers were fabricated to test the performance of spin detector contact NiFe/n-Si at different temperatures. It was found that this Schottky contact can not provide sufficiently low leakage current to enable room-temperature operation of spin transport devices. Pd/NiFe/Cu was used as the detector base of 10-μm vertical spin transport devices to improve spin detection efficiency, but it was found that Pd greatly reduces spin polarization, and the devices are unable to realize their design purpose.